Control system fob hydraulic



Jan. 8, 1946. L. A. CAMEROTA CONTROL SYSTEM FOR HYDRAULIC PRESSES Filed July 1, 1943 5 Sheets-Sheet 1 INVENTOR; Lozzzlsflamamza, P P V ATTO RNEYS.

.Jan. 8, 1946. A. CAMEROTA .CONTROL SYSTEM FOR HYDRAULIC PRESSES 5 Sheets-Sheet 2 Filed July 1, 1943 INVENTOR: LOU/ZS ,fl mmemm,

WITNESSFS:

ATTORNEYS.

L. A. CAMEROTA cou'moL SYSTEM FOR HYDRAULIC PRESSES Filed July 1, 1943 5 Sheets-Sheet INVENTOR;

- Louwfliwnemiw, BY 7014 Pp; v

ATTORNEYS.

- Jan. 8, 1946.

Jan. 8, 1946'. L. A. CAMEROTA CONTROL SYSTEM FOR HYDRAULIC PRESSES Filed July 1', 1943 5 Sheets-Sheet 4 WITNESSESr I INVENTOR:

o'ugi i wmeratw, BY M a r Q) MD). M

ATTORNEYS.

Jan. 8, 1946. 1.. A. CAMEROTA CONTROL SYSTEM FOR HYDRAULIC PRESSES Filed July 1, 1945 5 Sheets-Sheet 5 I. 05--- IFILJ w m m A INVENTOR; Louis 47. Camemm,

ATTORNEYS.

Patented Jan. a, 194

CONTROL SYSTEM Foa manure masses Louis a. mama, Burlington, N. 1., assignor to Machin Florence Pipe Foundry &

e Company;

Florence, N. 1., a corporation of New Jersey Application July 1, 1943, Serial No. 493,061

4 Claims. (01. -52) This invention" relates to control systems for hydraulic presses, and is more especially concerned with control systems for hydraulic presses having single reversely-acting ram and pull-back cylinders.

The chief aim of my invention is to make possible more rapid operation of presses of the kind referred to with a view toward securing increased output from them to the avoidance of injurious shocks or strains in the presses as the rams near the completion of their strokes in opposite direc- I Fig; 2 is a view like Fig. l with theram nearing the completion of its upward stroke.

Fig. 3 shows the ram quiescent in its fully raised position. I

In Fig. 4, the ram has started on its downward stroke; while Fig. 5 shows the ram nearing the completion of its downward stroke.

With reference first more particularly to Fig. 1 oi',these illustrations, thehydraulic press to be controlled is comprehensively designated by the numeral l, the same having a single-acting cylinder 2 for the ram 3, and a pair of single-acting pull-back cylinders whereof one is shown at 4 with its plunger 5 connected by a rod 6 to said ram, the other pull-back cylinder being at the opposite side of said ram cylinder. Oil or other liquid for operating the press I is stored in a reservoir l which is provided with a liquid level gauge 8 and a draw-off pipe 9. Mounted on the reservoir 1 is a pump in which, let it be understood, may be of any approved and well known reversible, rotary, variable delivery type, driven in the illustrated instance by an A. C. multi-phase electric motor II, and which draws liquid from said reservoir by way of a pipe I2 wherein the flow is restricted to one direction by a check valve l3. As shown, the pump It! has a laterally-protruding governing shaft [5 with a gear pinion l6 and rack ll whereby said shaft may berotated in opposite directions from a normal neutral position. Leading horizontally from the reservoir I is a pipe l8 of comparatively largediameter', which, through an elbow I9, is connected to a port ,the lower end of the pull-back cylinder 4; and

connected to the side or port B of said pump is a pipe line 25, 28, 21 which leads to the top of the ram cylinder 2 adjacent the port 29.

The provisions which have been made, in accordance with the present invention, for controling the press include a solenoid-actuated control valve 28 and a solenoid-actuated master valve 29, which are interposed in the pipe 23. The control valve 28 is biased by a spring 3'!) which tends to keep it open and is arranged to be closed upon energization of a solenoid magnet 3| associated with it. The master valve 29 on the other hand is oppositely biased by a spring 32 which tends to close it, and which is opened by means of a solenoid magnet 33. Cooperative with the port 20 at the top of the ram cylinder 2 is a suction-responsive filling check valve 35 which is yieldingly urged toward closed position by a spring 36, and which is operable by a fluid pressure cylinder 31 connected by a branch pipe 38 of smaller caliber, with the pipe 23 at a point between the control and master valves 28 and 29. Liquid flow in the pipe 38 may be regulated by the manually operable throttle valve shown at 39.

Connected to the pipe 23 across the control valve 28 is a shunt loop 40, 4| with an interposed adjustable throttle valve 42 to restrict flow therein. A normally closed pressure-responsive pilotoperated bleed valve 43 has its actuating cylinder connected by a small-caliber branch pipe 44 with the leg 4| of the shunt loop 40, and its ports by small branch pipes 45 and 46 respectively with the pipes l3 and 26, flow through the branch 46 being regulatable by a manually adjustable throttle valve 41. The pump governing elements I5- I l are arranged to be manually operated, through a bell-crank lever 48, by a vertical stroke rod 49 having spaced stop collars 50 and 5| thereon in the path of a lateral projection 52 on the ram 3. Somewhat-below the stop collar 5| the stroke rod 49 also carries a tapered. cam piece 53 to coact with the actuating arm 54 of a limit switch 55 which is aflixed to the side of the press frame. The starting lever shown at 56 is afllxed to a rock shaft 51 together with a horizontal arm 58 whereof the outer end is pivotally connected to the lower end of the stroke rod 49. The spring devices shown at 59 and 60 react upon the arm 58 from above and below to normally keep it and the pump governing elements l5-ll in neutral position with the pump ll idling. Threadedly engaged in a boss 5| of the lateral projection 52 on the ram 3 is a vertical rod 63 which at its upper end has an elongated cam head 65 to cooperate with the actuating arm 66 of another limit switch 61 affixed like the limit switch 55, to the side of the press frame at a higher elevation. For the purpose of adjusting the rod 83 in the projection 52, there is shown a hand-wheel 68 which is rotatively supported in a fixed bearing bracket 69 having a, spline in engagement with a longitudinal groove in said rod. Also mounted on the side of the press frame is a double push-button switch II for starting and stopping the pump motor II. The system is safe-guarded against derangement or injury by the safety valves 12, I3 and 14 respectively connected to the pipes 22, 24 and 28; the pressure in the latter pipe being at all times registered by the sight gauge shown at 15.

In addition to the electrical instrumentalities already referred to, the control system further includes a starter box I6, which may be of any suitable conventional type to which current is carried, through conductors 11, I8 and 19 from a power line, not shown, and from which leads 80, 8|, 8'2 and 83 extends to the motorstarting button switch 1|. Also extending from the box 18 are leads 85, 86 and 81 that carry the current to the motor II. The energization of the solenoid 33 of the master valve 29 is controlled by a relay 88, said valve 29 being held open while the motor II is running by reason of the fact that the coil 89 of said relay is connected across one phase of the current supply circuit of said motor by leads 90 and 9|. As a consequence of this arrangement, it will be evident that upon stopping of the motor II, the relay 88 will open and allow the valve 29 to close. The energization of the solenoid 3| of the control valve 28 is subject to a relay 92 under control of the limit switches 55 and 61 so that said valve is opened and closed during different conditions of press operation as later on explained. The wiring connections through which such operation is made possible includes a conductor 93 which extends from one terminal of the magnet coil 94 of the relay 92, and a conductor 95 which extends from the other terminal of said coil to one of the contacts of the limit switch 55. As shown, the limit switch 55 is connected in series with the limit switch 61 through conductors 96 and 91 whereof the latter extends to the lead 85 of the motor supply line. Still another conductor 98 extends from one of the lower contacts of the relay 92 to the conductor 96.

The operation of my improved control system is as follows: In Fig. 1, let it be assumed that the motor II is running, by movement of the starting button switch II in an obvious manner, and the press closed with the ram 3 all the way'down, after having compressed the material M with the pump ill in neutral condition and idling. Incidental to the conditions just stated, it will also be readily seen that the control valve 28 will be in closed position, due to the solenoid magnet 3| being energized, with no flow of operating fluid through the pipe line 22, 23, 24 due to the pump I0 idling. To efiect opening of the press, the operating lever 55 is thrown to the left as shown in Fig. 2 and the rod 49 thereby drawn downward, as a result of which the pump I0 is adjusted through the bell-crank 48, rack l1 and the pinion [5, to deliver liquid under pressure from its A side into the pip 22.

Concurrent with starting of such downward movement of the rod 49 the cam piece 53 thereon operates the actuating lever 54 of the limit switch 55 to open th latter. The circuit through the relay 92 is thereby broken and the solenoid 3| oi the valve-28 tie-energized to permit the control valv 28 to be opened by its spring 30, the valve 29 being already open by reason of being directly connected in circuit with the motor H as previously explained. Thus the liquid delivered from the A side of the pump ill will pass through the piping 22, 23 and 24 and the valves 28 and 29 into the bottom ends of the pullback cylinders 4 to raise the ram 3. Immediately as the pressure in the pipe 23 builds up sufflciently to start lifting the ram 3, the accumulating pressure in the branch pipe 44 will cause the valve .43 to be opened to relieve the pressure in the ram cylinder 2. The pumped liquid passing by way of the branch pipe 38 into the small cylinder 3'! at the top of the elbow fitting I9 will thereupon become immediately effective to open the valve 35 for relief of the pressure in the ram cylinder, and permit rapid draining of said cylinder by way of the large pipe l8 into the storage reservoir I. ,As the ram 3 begins to rise, the cam piece 65 will pass beyond the actuating lever 66 of the limit switch 61 which will thereby be opened without any change however in the set up. Somewhat thereafter, the lateral projection 52 on the ram 3 will engage the collar 50 and lift the rod 49. By this action the pump governing means is gradually moved toward neutral position with attendant decrease in the pressure and rate of delivery of the liquid to the pull-back cylinders 4, and at the same time the starting lever 56 will be shifted toward its normal upright position. As the fluid pressure decreases, the valves 35 and 43 will be moved to the closed positions in which they are shown in Fig. 3, under the influence of their springs, whereupon the remaining fluid in the top of the ram cylinder 2 will be obliged to traverse the smaller piping 21, 26, 25 at a greatly reduced rate. In this way the ram 3- will be effectively cushioned as it nears the completion of its up stroke and said ram comes gently to rest in the fully raised position as shown in Fig. 3 without jarring or straining of the press.

To lower the ram 3, the starting lever 56 is moved to the right as shown in Fig. 4 to raise the rod 49 and thereby cause reverse action of the pump [0 so that the liquid is now delivered under pressure from the B side of said pump through the piping 25, 26, 21 to the top of the ram cylinder 2. Immediately as the ram 3 starts to move, the valve 35 will open under the suction incidentally created and allow liquid to pass through the large pipe 18 from the reservoir I to the cylinder 2, while at the same time the pullback cylinders 4 will be permitted to drain by way of the piping 24, 23 and 22, the control valve '28 being still open as shown in Fig. 4. Under these conditions, the ram 3 will drop rapidly until it meets with resistance in encountering the material M on the platen of the press as shown in Fig. 5, whereupon the valve 35 will close, automatically to trap the liquid in the cylinder 2. Since at this stage the lever 56 is still in its rightward position, the pump ill will suck liquid through the check valve l3 in pipe l2 and such liquid will be forced by the pump it, via the B side of said pump and the pipe line 25. 26, 21, to the ram cylinder so that the ram 3 willthereafter be subjected to the full pressure of the liquid so delivered by said pump to comtion of its down stroke, the cam piece 65 on the threaded rod 63 will engage the actuating lever 66 of the limit switch 61 to close the latter, with attendant closing of the circuit through the magnet coil 94 of the relay 92 and energization of the solenoid 3| to close the control valve 28. As a consequence, the discharge from the' lift cylinders 4 will be obliged to by-pas around the now closed control valve 28 through the loop 40, 4| and so act to cushion further downward movement of the ram 3. Finally, as the ram 3 reaches the end. of its down stroke, the projection 52 thereon will engage the collar 5| on the rod 49 to depress the latter, as understandable from Fig. 5 with resultant gradual decrease in the rate of liquid delivery by the pump I0. Thus here again the movement of the ram 3 will be effectively checked to preclude jarring and excessive straining of the press. It is to be particularly noted that the construction of my improved control system is such as will enable stoppage of the ram 3 at any time simply by moving the actuating lever 56 to upright position to shift the pump governing means to neutral position. I

The speed of press closing after the ram 3 has reached a definite point at maximum speed in its downward stroke can be varied by adjusting the throttle valve 42.

Having thus described my invention, I claim:

1. A control system for a hydraulic press having a single acting ram cylinder and a single acting pull-back cylinder, said system including a reversible variable capacity pump with means for governing its operation; an electric motor for driving the pump; manually operable switch means for starting and stopping the motor; pipe lines respectively connecting the ram cylinder and the pull-back cylinder with the opposite sides of the pump; an electro-magnetically clo'sable con trolvalve in the pipe line of the pull-back cylinderra by-pass shunting the control valve with interposed throttle means for retricting flow therethrough; means operative to open the control valve with initiation of pressure liquid flow to the pull-back cylinder and, a the ram nears the completion of its down stroke, to cause grad the controlvalve so that the liquid draining from V the pull-back cylinder is obliged to traverse the by-pass aforesaid; a self-closing master valve in v the pipe line of the pull-back cylinder between the latter and the by-pass; and electromagnetic actuating means for the master valve connected in circuit with the motor to keep said master valve open while the motor runs.

2. The invention according to claim 1, wherein the control valve is biased by spring means tending to keep it open but is closed by the electromagnetic means; wherein a switch operated upon commencement of the u stroke of the ram breaks the circuit through said magnetic means and permits the control valve to open; and wherein said switch can'be automatically operated by the ram as the latter nears the completion of its down stroke, to re-establish the circuit through said magnetic means and thereby efiect re-closing of said control valve.

3. A control system for a hydraulic press having a ram cylinder and a pull-back cylinder, said system including a reversible variable capacity pump with means for governing its operation;

means of the control valve; cam means on the stroke rod for opening one ofthe switches, as said rod is shifted to initiate delivery of the liquid by the pump to the pull-back cylinder, and thereby to ole-energize the magnetic operatin means and effect opening of the control valve; and means carried by the ram and adapted as V the ram nears thecompletion of its down stroke to close the other switch and effect rep-energize tion of the magnetic means for closing of the control valve whereby the liquid, at that time displaced from the pull-back cylinder, is obliged to traverse said by-pass.

4. A control system for a hydraulic press according to claim 3, in which the means carried by the ram for actuating the second switch is in the form of an axially-adjustable rod with cam means thereon to cooperate with the other or second mentioned switch.

LOUIS A. CAMEROTA. 

